The present invention relates to an electromagnetically or hydraulic actuated pulse driven two position ratchet mechanism for valve deactivation in push rod and overhead camshaft internal combustion engines. This pulse system can be adapted to a push rod configuration, or at a rocker location of an overhead camshaft valve drive. For improved fuel economy strategic cylinders would be deactivated by inducing a break in the valve drive linkage using a time sensitive switching device activated by an energy conserving pulse versus the continuous power on versions.
Traditionally, valve deactivation devices are complex designs employing a remote located solenoid using a drive linkage which is held to the on position by a continuous energy draw to a solenoid coil, or continuous hydraulic pressure. Valve deactivation systems (VDS) date back to the early 1970s. The first successful system was a latchable fulcrum for pushrod rocker arms on Cadillac V8 engines in 1981. Further present day valve deactivation system examples are those of INA Motor Enelment uses a 3 lobe camshaft, dual bucket configuration for overhead camshaft engines wherein a high lift/no lift event is achieved by driving the outer bucket with the higher profile peripheral camshaft lobes for high lift, and driving the central camshaft lobe and bucket for no lift. This system employs a sliding hydraulic operating pin, which switches to connect outer bucket to inner bucket to generate, timed lift event. Another INA design uses a two-piece valve rocker where the primary rocker section driven by the camshaft is connected or disconnected to a secondary rocker activating the valve by a sliding pin. It should be appreciated that all valve deactivation systems need a power supply, and a driven switching engagement element such as a pin, which is very critical to operation. The reason for this preciseness is you only have the rest time, or camshaft base circle time when the valvetrain rockers and pushrods are not in motion for insertion of a locking pin or switching element. It also should be noted that the switching sequence time decreases, as engine RPM becomes higher. Therefore, it is an advantage to use a time compatible geometry for switching element.
The present invention provides a compact concentrically located solenoid drawing a short energy pulse to drive a ratcheted geometric switching key to join or detach adjacent moving valvetrain elements. A significant feature of this design is its fast, direct solenoid reaction time, and specialized rotative locking key which moves at the same velocity as the retaining member it is locked to for valve deactivation.
It is therefore a primary object of this invention to provide a specialized locking key which, unlike a pin or latch, when driven will provide superior performance within camshaft base circle diameter time window.
It is another object of this invention to locate the driving armature close to the locking key to lower the mass of the connecting members needed to switch the locking key for faster operation.
It is yet another object of this invention to design a solenoid concentrically to delete remote connecting members, simplify design, and lower drive members for fast reaction time.
It is still another object of this invention to drive the locking key to an engaged position with one energy pulse.
It is yet another object of this invention to combine the solenoid locking system and tappet in one compact assembly for push rod application.
It is a further object of this invention to be adaptable for location high in a cylinder head for easy service.
It is still a further object of this invention to adapt the solenoid and locking key assembly to a primary and secondary rocker for valve deactivation on overhead camshaft engines.
To achieve the foregoing objects, the present invention provides an electromagnetically pulse driven two-position specialized ratchet mechanism for valve deactivation. One advantage of the present invention is a low mass special key for faster response is used operating in camshaft base circle diameter time window.
Another advantage of the present invention is that the driving armature can be located very close to the switching key for fast activation.
A further advantage of the present invention is that the solenoid is designed concentrically creating a compact unit deleting the need for remote connecting elements.
A further advantage of the present invention is that the locking key is driven to the engaged position by one pulse, thus conserving the energy needed to activate versus continuously applied versions.
Still another advantage of the present invention is that the activation unit can be adapted to both push rod and overhead camshaft engines.
Yet still another advantage of the present invention is that the electro solenoid system does not contend with the low RPM oil pressure, and oil pump energy draw of hydraulic systems.
Another advantage of the present invention is that the locking key has more latitude in build tolerancing.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.